Solvent deasphalting of residual oils with wash oil to remove metal contaminants



United States Patent SOLVENT DEASPHALTING OF RESIDUAL OILS WITH WASH OIL TO REMOVE METAL CON- TAMINANTS William 0. Webber, Baytown, Tex., assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Application September 20, 1954, Serial No. 457,049

7 Claims. (Cl. 19614.46)

crude oils contain such an amount of metal contaminantsas to be undesirable feed stock for catalytic cracking operations. U

The present invention may be briefly described as' involving the use of a residual oil or fraction thereof derived from Hawkins crude oil as a wash oil in deaspha-lting a residual feed stock to serve as a selective solvent removing metallic contaminants. from said feed stock. v

More specifically, the present invention is'directed to a procedure whereby a residual petroleum fraction, that is a fraction containing a major portion of components boiling above 900 F. and contaminated with a substantial amount of metal contaminants which have as their origin metallic contaminants present in the crude oil as produced from the earth, is treated to secure a fraction substantially free from metallic contaminants. The treating step is carried out by continuously introducing a stream of feed stock into a deasphalting zone, continuously introducing a stream of residual oil derived from crude oil produced from the Hawkins field as a wash oil into the tower at a point above the point of introduction of the feed stock, continuously introducing a stream of liquefied normally gaseous hydrocarbon into the tower at a point below the point of introduction of the feed stock, continuously withdrawing a solution of deasphalted oil free from metallic contaminants from the top of the tower and continuously withdrawing an asphalt phase containing substantially all of the metallic contaminants introduced into the tower from the bottom of the tower. The resultant deasphalted oil substantially free from metallic contaminants is a desirable feed stock for a catalytic cracking process whereas the residual oil containing the metallic contaminants which is charged to the deasphalting zone is undesirable for use as a feed stock for a catalytic cracking process.

The residual oil derived from a crude petroleum from the Hawk-ins field in Texas may be described generally as an oil derived from Hawkins field crude free from components boiling below about 650 F. Characteristics of Hawkins residual oils suitable for use as the wash oil in a process of the present inventiom are set out hereafter in Table I:

TABLE I Typical wash 01! Inspection:

Percent on Crude. 29. 0 Gravity, API 4. 7 4. 9 Viscosity, SSF 275 F 645 Conradson Carbon, Wt. percent... 19. 8 24. 7 Contaminants, #/1,000 bbls 352 N 10. 2 9. 5 V- 15. 0 16. 5 F 7. 0 7. 4

The present invention will be described in greater detail in conjunction with the drawing in which Fig. l is in the form of a diagrammatic flow sheet illustrating one procedure for carrying out the deasphalting step for removing metallic contaminants from the residual oil; and,

Fig. 2 is in the form of a diagrammatic flow sheet illus trating another procedure for treating a residual fraction derived from crude oil to remove metal contaminants therefrom.

Turning now specifically to the drawing and first to i A residual fraction derived from a crude oil is charged through inlet line 11 and passes from a distributor 12 into a central part of the tower with liquefied normally gaseous solvent introduced into the bottom of the tower through inlet line 13 to flow upwardly in the tower countercurrent to the residual fraction. A Hawkins residual oil is introduced as the wash oil through line 14 and discharged through distributor 15 in an upper portion of the tower so that it passes downwardly countercurrently to the up-fiowing solvent. A solution of deasphalted oil substantially free from metallic contaminants is withdrawn from the top of the tower through outlet line 16 and an asphalt fraction containing substantially all of the metal contaminants introduced into the tower A with the charge stock as well as those metal components introduced into tower A with the wash oil is withdrawn through outlet line 17.

Another procedure for removing the metal contaminants from a residual oil is shown in Fig. 2. In this figure, tower A is similar to tower A of Fig. 1. In Fig. 2 a residual oil derived from a crude and contaminated with a substantial amount of metal contaminants is introduced through inlet line 30, and discharged through distributor 31 into the central part of the tower. Liquefied normally gaseous hydrocarbon is introduced as solvent through line 32 into the lower portion of the vessel A so that it passes upwardly countercurrent to the residual oil charged. A Hawkins residual oil is introduced as the wash oil into tower A by line 33 and distributor 34 which is above distributor 31 so that the wash oil contacts the solution of residual oil as it flows upwardly in the tower. An asphalt fraction consisting of a large part of the introduced wash oil and of asphalt separated from the residual oil charge stock and containing substantially all of the metal contaminants introduced into tower A both with the residual oil and with the wash oil is withdrawn from the bottom of the tower through ing discharged into settling drum D. In settling drum D a phase separation takes place with a lighter phase consisting of a solution of deasphalted oil substantially free from metallic contaminants being withdrawn through outlet line 38, this material after freed from solvent being a desirable charge stock for a catalytic cracking process. The heavier phase is withdrawn from the bottom of drum D through line 39 and pumped by pump 40 into line 33 where it is introduced as the wash oil in tower A as previously described.

The procedure of Fig. 2 differs from the procedure of Fig. 1 in having an additional stage. By' way of example, if a 10% wash used in Fig. 1 causes a removal of 75% of metal components, the additional stage used in Fig. 2 should increase the metal removal" from 75% to approximately 92%.

The inspection of residua from the distillation of typical crude oils charged to refinery operations are set out hereafter in Table II. In Table H, columns 1,2, 3 and 4 show the'characteristics respectively of residual derived from a mixture of Gullf Coast and West'Texas crudes, a. West Texas crude, a Panhandle crude and a Lagunillas crude.

The catalytic. cracking of fractions of petroleum oils is wellknown to the art. A description of such a catalytic cracking process may be found in U. S. Patent 2,587,554, issued' February 26, 1952, in the. name of John Weikart.

In suchcatalytic cracking operations it has been found that if the charging stock contains as much as three pounds of nickel per thousand barrels of charge stock, the catalytic cracking process is adversely affected. Other metal components such as vanadium and iron are undesirable but are less troublesome than nickel; in general on a weight basis it may be considered that vanadium is perhaps Vs as troublesome as nickel and iron is perhaps /2 as troublesome as vanadium. Hereafter in the specification and claims where the expression equivalent to three pounds of nickel per thousand barrels of oil'" appears, it is to be understood that this is intended to encompass the metal components nickel, vanadium and iron with nickel used at its full weight value, vanadium consider at approximately /5 its actual weight value and iron considered at approximately its actual weight value.

In carrying out the deasphalting step in the present invention where a Hawkins residual oil is used as a wash oil to remove selectively the metal contaminants from the residuum charge, the solvent used in a liquefied normally gaseous hydrocarbon. The use of liquefied normally gaseous hydrocarbon is well known in the deasphalting art. As specific examples of materials which could be used may be mentioned ethane, propane, propylene, butylene, butane and mixtures thereof. Because of pressure limitations in the operating equipment, it is preferred to use butane, propane, propylene and butylenes or mixtures thereof with a desirable commercial mixture consisting of 30% butane and 70% propane.

The preferred amount of solvent employed in the deasphalting step is 'within the range of 2 to .10 volumes of solvent per volume of residual oil charged to the deasphalting step. As a specific example it has been found that 3.2 volumes of solvent .per volume of residual oil charged is a desirable commercial ratio.

The temperature at whichthe deasphalting step is conducted may be within the range of to 300 F.

There may be a temperature gradient in the deasphalting step with the highest temperature at the deasphalted oil outlet. The temperature gradient may be within the range of 0 to 100 F. As a specific example a 20 gradient may be used with the top of the tower, at the point where the deasphalted oil is withdrawn being maintained at 180 F. and the bottom of the tower where the asphalt is withdrawn with the residual oil being F.

In carrying out the prooess oh the present invention it will .usually .be..fonnd..that..meta1 content of the deasphalted oil-isjle'sss than-10% of the metal. contaminants introduced -into the deasphalting zone andralsozless than the equivalent of one pound of nickel per 1000 barrels of oil.

In order to ,illustratvfurther the advantages of the present inventionf'thefollowing'example is given:

The feed stock treated. wasa blend. ofnonlube residua having the characteristics setout hereafter in Table III:

TABLE HI Sp. g I 10094 0.0. flash, 635 Visc.:

. SSE/210 725 SSF/27'S. 108 Conradson .Qarbom; gp'ercent 18.7 Bomb Sulfur, percent.. 3405 Agg. .Ash ire/4000 bbl- 105.9 Ash-analysis:

V--#/1000 b 14.5 Ni. 13.0 Fe; 6.2 Na 14.8

Two '-dea' sphalting'runs were made with the operating conditions -set-'out hereafter in'Table In Table IV, column -1 shows a procedure inwhich' the feed stock was ideasphaltedewithout the use: (if awash oil whereas column 2 shows a procedure in accordance with the present invention-in which 20 partsof a Hawkins residuum was introduced as-wash oil for treating --80 .parts of feed stock having the characteristics set out heretofore in Table IH. It will be seen that in column 2 where the procedure is carried out in accordance with the present invention, the nickel contaminants of the deasphalted oil are .30 pounds per thousand barrels of oil whereas in column 1 Where no wash oil was used, the nickel contaminants of the deasphalted oil are .67 pounds per thousand barrels.

TABLE IV Operating conditions and inspections Residuum charge 100.0 80 Wash 01L 0 20 Operating Conditions:

Solvent to 011 Ratio 3. 5 2. 95 Solvent Composition, Vol. Percent-- 03 71. 3 69. 5 O4 28. 7 30. 6 Temperature, F.-

Tower top 171 Tower middle 161 160 Tower bottoms..- 151 150 Fromm-9,8. s. t. g 400 400 Deasphalted il:

Yield, Vol. Percent... 49.0 44. 0 Gravity, API 18. 2 19. 0 Viscosity, SSU' 210 F.. 379 370 Oonradson Carbon, Wt. Percent 4. 43 3. 67 Bomb Sulfur, Wt. Percent 1. 58 1.99 Contaminants, #/1;000 bbls.-

Agg.- h 1. 12 l 0. 67 0.30

It will be .noted .as shown from the typical analysis contains substantial amounts of nickel but as shown by the example, the use of Hawkins residuum as a wash oil results in a deasphalted oil containing a very low amount of nickel and particularly useful as a feed stock for a catalytic cracking process. It will thus be seen that Hawkins residual oil has an unexpected characteristic that it has selective action for removing contaminating metallic constituents in a deasphalting process so that the deasphalted oil is substantially free from metallic contaminants. As previously explained in referring to Hawkins residual oils in the specification and claims of the present case, the material referred to is secured by the distillation of crude oil from Hawkins field and is free from components boiling below 650 F.

While specific examples have been given illustrating the practice of the present invention it will be understood that these specific examples are given by way of illustrative purposes only and not by way of limitation.

The invention claimed is:

1. A method for treating a petroleum fraction feed stock containing a major portion of components boiling above 900 F. and contaminated by a substantial amount of metallic contaminants including no less than the equivalent of 3 pounds of nickel per thousand barrels of oil consisting of the steps of continuously introducing a stream of said feed stock at a selected point in a deasphalting tower the contents of which are maintained at a temperature within the range of 100 to 300 F., continuously introducing a stream of a residual fraction derived from Hawkins crude free from components boiling below approximately 650 F. into said tower as a wash oil at a point above the point of introduction of said feed stock, continuously introducing a stream of liquefied narmally gaseous hydrocarbon into the tower at a point below the point of introduction of the feed stock in an amount within the range of 2 to 10 volumes of liquefied normally gaseous hydrocarbon per volume of feed stock, continuously withdrawing a solution of deasphalted oil in liquefied normally gaseous hydrocarbon from a point in the tower above the point of introduction of said wash oil, said solution of oil containing no more than 10% of the metallic contaminants introduced into said deasphalting tower and no more than the equivalent of one pound of nickel per thousand barrels of oil and contin' uously withdrawing from a point in the tower below the point of introduction of said steam of liquefied normally gaseous hydrocarbon an asphalt phase containing substantially all of the metallic contaminants introduced into said zone.

2. A method in accordance with claim 1 in which there is a temperature gradient within the range of to 100 F. between a lower temperature point at which the asphalt phase is removed from the tower and a higher temperature point at which the deasphalted oil is removed from said tower.

3. A method in accordance with claim 1 in which there is a temperature gradient within the range of 0 to 100 F. between a lower temperature point at which the asphalt phase is removed from said tower and a higher temperature point at which the deasphalted oil is removed from said tower and in which approximately one volume of residual oil derived from Hawkins crude oil and free from constituents boiling below approximately 650 F. is introduced into the deasphalting zone for each 4 volumes of feed stock.

4. A method in accordance with claim 1 wherein the said solution of oil withdrawn from the said tower has continuously admixed therewith a Hawkins crude oil residual fraction substantially free from components boiling below about 650 F., wherein the resultant mixture is continuously charged to a settling zone under conditions to obtain phase separation, wherein a lighter phase consisting of a solution of said deasphalted oil containing a still further reduced amount of metallic contaminants is continuously withdrawn from said settling zone and wherein a heavier asphalt phase is continuously withdrawn from said settling zone.

5. A method for treating a petroleum fraction feed stock containing a major portion of components boiling above 900 F. and contaminated by a substantial amount of metallic contaminants including no less than the equivalent of 3 pounds of nickel per thousand barrels of oil consisting of the steps of continuously introducing a stream of said feed stock at a selected point in a deasphalting tower, the contents of which are maintained at a temperature within the range of to 300 F., continuously introducing a stream of a wash oil material into said tower at a point above the point of introduction of said feed stock, continuously introducing a stream of liquefied normally gaseous hydrocarbon into said tower at a point below the point of introduction of the feed stock in an amount within the range of 2 to 10 volumes of liquefied hydrocarbon per volume of feed stock, continuously withdrawing a solution of the deasphalted oil in said liquefied hydrocarbon from a point in the tower above the point of introduction of said wash oil, continuously withdrawing an asphalt phase containing substantially all of the metallic contaminants from a point in the tower below the point of introduction of said stream of liquefied hydrocarbon, continuously admixing with said solution of oil about 1 volume of a Hawkins crude oil residual fraction substantially free from components boiling below about 650 F. per 4 volumes of said feed stock, continuously charging said mixture to a settling zone under conditions to obtain phase separation, continuously withdrawing a lighter phase consisting of said solution of oil in said liquefied hydrocarbon in further purified form, continuously withdrawing from said settling zone a heavier asphalt phase, and continuously charging said heavier asphalt phase to said deasphalting tower as said stream of wash oil material.

6. A method for treating a petroleumfraction feed stock containing a major portion of components boiling above 900 F. and contaminated by a substantial amount of metallic contaminants including no less than the equivalent of 3 pounds of nickel per 1000 barrels of oil, consisting of the steps of continuously introducing a stream of said feed stock at a selected point in a deasphalting tower, continuously introducing a stream of residual fraction derived from Hawkins crude free from constituents boiling below approximately 650 F. into said tower as a wash oil at a point above the point of introduction of said feed stock, continuously introducing a stream of liquefied normally gaseous hydrocarbon into the tower at a point below the point of introduction of the feed stock, continuously withdrawing a solution of deasphalted oil substantially free from metallic contaminants in liquefied normally gaseous hydrocarbon from a point in the tower above the point of introduction of the wash oil and continuously withdrawing an asphalt phase containing sub stantially all of the metallic contaminants introduced in the feed stock from a point in the tower below the point of introduction of said liquefied normally gaseous hydrocarbon.

7. A method in accordance with claim 6 in which the deasphalted oil contains nor more than 10% of the nickel contaminants introduced into the deasphalting tower with the petroleum fraction and no more than 1 pound of the equivalent of nickel per 1000 barrels of oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,009,710 Goodwin July 30, 1935 2,053,485 Lindeke et al. Sept. 8, 1936 2,070,384 'Iuttle Feb. 9, 1937 2,687,982 Baumann Aug. 31, 1954 2,727,848 Georgian Dec. 20, 1955 2,727,853 Hennig Dec. 20, 1955 

1. A METHOD FOR TREATING A PETROLEUM FRACTION FEED STOCK CONTAINING A MAJOR PORTION OF COMPONENTS BOILING ABOVE 900*F. AND CONTAMINATED BY A SUBSTANTIAL AMOUNT OF METALLIC CONTAMINANTS INCLUDING NO LESS THAN THE EQUIVALENT OF 3 POUNDS OF NICKEL PER THOUSAND BARRELS OF OIL CONSISTING OF THE STEPS OF CONTINUOUSLY INTRODUCING A STREAM OF SAID FEED STOCK AT A SELECTED POINT IN A DEASPHALTING TOWER THE CONTENTS OF WHICH ARE MAINTAINED AT A TEMPERATURE WITHIN THE RANGE OF 100* TO 300*F., CONTINUOUSLY INTRODUCING A STREAM OF A RESIDUAL FRACTION DERIVED FROM HAWKINS CRUDE FREE FROM COMPONENTS BOILING BELOW APPROXIMATELY 650*F. INTO SAID TOWER AS A WASH OIL AT A POINT ABOVE THE POINT OF INTRODUCING OF SAID FEED STOCK, CONTINUOUSLY INTRODUCING A STREAM OF LIQUIEFIED NARMALLY GASEOS HYDROCARBON INTO THE TOWER AT A POINT BELOW THE POINT OF INTRODUCTION OF THE FEED STOCK IN AN AMOUNT WITHIN THE RANGE OF 2 TO 10 VOLUMES OF LIQUEFIED NORMALLY GASEOUS HYDROCARBON PER VOLUME OF FEED STOCK, CONTINUOUSLY WITHDRAWING A SOLUTION OF DEASPHALTED OIL IN LIQUEFIED NORMALLY GASEOUS HYROCARBON FROM A POINT IN THE TOWER ABOVE THE POINT OF INTRODUCTION OF SAID WASH OIL, SAID SOLUTION OF OIL CONTAINING NO MORE THAN 10% OF THE METALLIC CONTAMINANTS INTRODUCED INTO SAID DEASPHALTING TOWER AND NO MORE THAN THE EQUIVALENT OF ONE POUND OF NICKEL PER THOUSAND BARRELS OF OIL AND CONTINOUSLY WITHDRAWING FROM A POINT IN THE TOWER BELOW THE POINT OF INTRODUCTION OF SAID STEAM OF LIQUEFIED NORMALLY GASEOUS HYDROCARBON AN ASPHALT PHASE CONTAINING SUBSTANTIALLY ALL OF THE METALLIC CONTAMINANTS INTRODUCED INTO SAID ZONE. 